318 Making Power

Les Szabo · Post by **Les Szabo** » Tue Feb 24, 15 9:24 pm

Ah so thats why you went so quick Jon

...a lot of the boys stateside go that route over a 727, worth a few 1/0ths.

Les

Dave81 · Post by **Dave81** » Tue Feb 24, 15 9:26 pm

Cheers Les.......

Jon Connolly wrote:Dave

The 904 is a very capable gearbox, I wouldn`t necessarily bin it off. I had one in my pick up truck behind a 575 hp 408 and it was as good as gold.

Funny you mention that, been researching the changes and it's probably the only piece I'd keep. Lighter than the 727 from what I've read and can be made to handle the power as you have found!

Jon Connolly · Post by **Jon Connolly** » Tue Feb 24, 15 9:29 pm

Dave81 wrote:Cheers Les.......

Jon Connolly wrote:Dave

The 904 is a very capable gearbox, I wouldn`t necessarily bin it off. I had one in my pick up truck behind a 575 hp 408 and it was as good as gold.

Funny you mention that, been researching the changes and it's probably the only piece I'd keep. Lighter than the 727 from what I've read and can be made to handle the power as you have found!

Yes definately worked well, used the sb 727 as well with same torque convertor and I think the 904 was better. Alot of the yanks using them now

MilesnMiles · Post by **MilesnMiles** » Tue Feb 24, 15 10:13 pm

Dave, Les is right about the XE262 cam; lots of low down torque and I liked it I my old Dart 360,
The real power killers as you know are low comp pistons and small valve heads.
Have. A word with Dave/Longshot, his 318 is a good un.

Dave-R · Post by **Dave-R** » Wed Feb 25, 15 9:19 am

Jon Connolly wrote:Dave

The 904 is a very capable gearbox, I wouldn`t necessarily bin it off. I had one in my pick up truck behind a 575 hp 408 and it was as good as gold.

With that power level and the stall speed it would need it is not going to last long without some internal work like the clutch pressure springs at least.

I managed to knack a 904 trying to do burnouts with a stock 2bbl 318.

MilesnMiles · Post by **MilesnMiles** » Wed Feb 25, 15 9:53 am

Dave, before you spend another dollar, fit that axle. You will be amazed at how much it will wake the car up. I still remember going from 2.76 to just 3.23 gears and all off a sudden with the same motor you had I could chirp the tyres and enjoy something akin to acceleration.

Blue · Post by **Blue** » Wed Feb 25, 15 10:58 am

Having built more than a few 904's, I can't imagine they would last too long with 500+ HP. The internals are so much smaller than a 727, and the contact area of the bands and clutches are tiny in comparison. If you didn't break it you'd be wearing it out pretty quick. Still, if you got a year of racing out of it and just needed to freshen it up, the HP and weight saving would be worth it IMO. If the Valiant was auto I'd definatly be experimenting with a 904.

Dave81 · Post by **Dave81** » Wed Feb 25, 15 2:02 pm

Thanks chaps.

Low Comp 318 related:
Been doing a bit more research....Apparently the '302' casting heads from the 85-91 dodge cars are a good swap. Small combustion area, closed chamber heads.

These with a 262 cam should give a good return.....or so I've read on the US sites??

These should also help increase the compression ratio..........Thoughts please?

Les Szabo · Post by **Les Szabo** » Wed Feb 25, 15 2:51 pm

Yes definately Dave, these are the ones used in the 400hp article, BUT, they come with small valves, will need to cut the seats for larger valves, and need a lot of porting = £££'s to give enough cfm (215) to make the power, they will also need milling depending on how far down your slugs are in the hole to get your 9.8:1 CR. These heads are also prone to cracking so getting a good pair isn't easy and risky. Magnum heads are a good option and require little or no porting, have reasonable flow and come with 1.92/1.625 valves and are around 59cc but you will need the rockers and different lifters and oil through pushrods. A pair of Indy heads like Miles has is the best option in my opnion, at £1500 as they are all complete, require no work and are a bolt on, have 62cc chambers which could be milled some when ordering and at that flow (271@.550") will work on any 340/360/408 you may want to build in the future, they flow great, a bit ott for a 318 but are plenty good for nearly 500hp.

With a good head/.480"+ cam etc., you will need to rev it of course, a loose-ish verter and those 3.55 gears is a must, a good stock bottom end will handle 6000rpm all day long cast crank or not! A good gearbox rebuild with shift kit will be on the cards as well, starting to mount up isn't it. But as Miles said, before you do anything, run the 3.55's and that will wake it up some and you may be happy with that for a while till you get some spondoolies.

Les

Bozwell · Post by **Bozwell** » Wed Feb 25, 15 7:33 pm

thought this looked interesting and should be similar for the Mopar engine?

Jon Connolly · Post by **Jon Connolly** » Wed Feb 25, 15 9:09 pm

Dave wrote:
Jon Connolly wrote:Dave

The 904 is a very capable gearbox, I wouldn`t necessarily bin it off. I had one in my pick up truck behind a 575 hp 408 and it was as good as gold.
With that power level and the stall speed it would need it is not going to last long without some internal work like the clutch pressure springs at least.

I managed to knack a 904 trying to do burnouts with a stock 2bbl 318.

Dave / Blue

For the sake of clarity I should have said the 904 is a good starting point ... my transmission is not a std 904

Dave81 · Post by **Dave81** » Wed Feb 25, 15 9:17 pm

Thanks for the long reply Les.......Much Appreciated

Think the reality, and the most cost effective way, is to run as is until I can drop in the unit the car requires.

Rear end swap is good for either, so agree with you and Miles! Will look at getting this done later in the year.......

Thanks for the link Boz.......